The invention relates to a hand tool, in particular a screwing tool and preferably a screwdriver or a wrench, and also pliers, a clamping tool or alternatively a file, having a recess profiled working face.
The invention also relates to a process for profiling working faces on tools of the type described above.
German utility model DE 94 00 780.2 U1 has disclosed a tool of the generic type. The utility model describes a screwdriver bit for crosshead screws, in which the working faces are profiled in linear form, with alternating recesses and elevations being formed. A channel profile with ribs flanking the channel is formed. During production of a screwdriver bit of this type, first of all the ribs are stamped. Then, the tool is hardened. The influences on the surface during hardening also act on the ribs. In the case of an excessively brittle tool, in which hard ribs project out of a hard base body, an excessive notch effect is produced. This can only be avoided by setting a lower surface hardness. However, this leads to relatively soft ribs which can then also rapidly become worn. In this context, one is faced with the problem that, on the one hand, a wear-resistant rib entails excessive brittleness of the tool, while, on the other hand, avoiding the brittleness of the tool as a whole leads to soft ribs, which therefore become worn.
Therefore, the prior art also uses other methods in order to increase the surface roughness of screwdriver bits. For example, DE 40 29 734 A1 and EP 0 521 256 A2 show the coating of working faces with particles of friction material. GB 950 544 and DE 197 20 139 C1 show a combination of surface profiling and coating.